It's a question to which the answer has been hotly debated: Why ARE we attracted to the people we're attracted to?

One theory which goes some way towards understanding this is that some people have a certain 'type,' or find a certain type of feature irresistible.

While it's not always as straightforward as this for a lot us, it may just be for men.

So what is it that they're drawn to which elicits attraction? Eyes? Mouth? Chin?

In fact, as a study shows, it's not strictly any one of these one features - but how 'simple' overall a woman's face is perceived to be.

Because the 'simpler' the face, the easier it is to cognitively process, making it, apparently, more pleasing to the eye.

But what is it that's meant by 'simple' - and how can what's often perceived to be a very subjective process be explained?

The science of beauty

169 men recruited from the south of France were shown a succession of two sets of random women's faces on a computer and asked to rank them between zero (lowest attractiveness) and 20 (highest).

A lack of unusual or distinguishing features are easier to process

While this may sound like another bored Friday night playing on Tinder, the researchers adapted the study to more accurately find commonalities in the results, controlling the women's ages, skin roughness and facial symmetry.

The faces which were rated as being the most attractive were the ones which were 'sparsely coded'.

So, depressingly, the ones which were easiest to process in the visual cortex (the part of the brain responsible for processing visual information) which were symmetrical, 'plainer' and with no major distinguishing features.

Sparse is sexy

The research findings may also go some way to explain why using emoticons is attractive, and why we find certain logos appealing.

But how many of us do actually have a symmetrical face?

Professor Bill von Hippel told News AU "This is part of the reason why ubiquitous brands are highly preferred; we see the Nike swoosh or the word Coke and it’s processed easily by virtue of its familiarity and that makes it more positive."

He continues: "Think about an emoticon, you have two dots and a curved line that immediately everyone processes as a smile. It's sparse, it’s plain. It's familiar, and it's easy to understand."

And something for the ladies - model David Gandy apparently has a near perfectly symmetrical face